Oscillator



Oct. 29,1946;

E- TURNER, JR

OSCILLATOR Original Filed March 23, 1936 v Fla).

INVENm r E 4W1 nrner J), W fiifi.

Patented Oct. 29, 1946 FFICE OSCILLATOR Edwin E. Turner, Jr., West Roxbury, Mass, as-

srgnor, by mesne assignments, to Submarine Signal Company, Boston, Mass., a corporation of Delaware Original application March 23, 1936, Serial No. 70,365. Divided and this application October 14, 1937, Serial No. 168,920

7 Claims.

The present application is a division of my copending appl cation Serial No. 70,365, filed March 23, 1936, entitled Oscillators,

The present invention relates to a device for producing mechanical vibrations and in particular mechanical vibrations having a rapid rate of oscillations within the range adapted to produce in a proper medium, particularly in Water as in submarine signaling, compressional waves above the ordinary range of audibility to the human ear.

In the present invention the vibrations of the nature described above are produced over a large vibratory surface in such a manner that the propagation of the waves in the medium is in a beam, although for lower frequencies the beam may be spread to form a radiating cone of desired angular opening, the factors controlling the size of the opening depending upon the relation of the wave length, the area and form of the vibrating surface in a manner known in the prior art,

In the present invention the beam is generated by means of a series of elements operating simultaneously in a plate or vibratory surface, the relationship of the length of the elements on the plate, their masses and the thickness of the plate, conforming to the principles laid down in the companion Edwin Turner application, Serial No. 677,179, filed June 23, 1933. In the present invention the elements impressing the vibratory energy on the plate may be either magnetostrictive in which the mechanical vibrations are developed through the magnetostrictive effect of the flux passing through the elements themselves, electrodynamic or magnetic. In the present application the embodiment including the magnetostrictive system is shown and described.

At very high frequencies such as those within the range of 20,000 cycles per second and higher, there is a distinct tendency for electric current to crowd near the surface of the conductor and as a result in magnetostrictive and nickel elements, therefore, the flux and magnetostrictive action take place to the greatest degree near the external surface. ference in vibratory stresses longitudinally in Various parts of the nickel and as a result the nickel elements may not operate at the maximum efiiciency. It is highly desirable, however, on account of the high frequencies and the shortwave-lengths that result, to drive the vibratory surfaces at a large number of points and this the applicant has accomplished in his prior application referred to above. However, in the pres- This also may cause a dif-' out application this is also accomplished and at the same time the magnetostrictive elements are operated more efficiently because of a decrease in the mechanical and electrical losses as will appear from the description in the specification.

The invention will be more fully understood from the description of the embodiment given below and illustrated in the drawing in which Fig. 1 shows a plan view with a portion of the top case removed, Fig. 2 shows a section taken on the line 2-2 of Fig. l and Fig. 3 shows .an enlarged detail of a portion of Fig.2.

Figs. 1, 2 and 3 show a spiral shaped magnetostrictive element, In this embodiment as shown in Fig. 2 there is provided a heavy plate All which has on the inside a recessed portion 41 in which there is placed a magnetostrictive sheet 42 wound in a spiral as more clearly indicated in Fig. 1. On the outside of this sheet there is positioned a conductor 53 which also extends around the entire spiral to the inside it making the elements 43 and 4 1 one piece of material. This may be readily seen in Fig. l at the center of the spiral where the element 44 continues around the end of the magnetostrictive member 42. The member 64 does not extend all of the way up on both sides of the magnetostrictive member 42 but is concentrated near the lower end adjacent the plate. The magnetostrictive elements are mounted in the plate by means of some metallic material 45 of suitable melting point to hold the spiral to the plate and yet not change the characteristic of the nickel elements themselves. The element surrounding the nickel spiral is supplied with current by means of the conductors 46 and 41 which in effect completes one turn of a coil about the magnetostrictive element 42 and therefore when supplied with current induces a flux therein longitudinally along the axis of the spiral elements.

An enlarged section of a portion of the conductor shown in Fig. 2 is shown in Fig. 3 and indicates quite clearly the relative sizes and positions of the magnetostrictive member 42 and the surrounding conductor 44. The surrounding conductor 4 is preferably sufficiently long to insure the induction of the magnetostrictive flux in a position close to the node in the spiral.

The conductive elements 43 and 44, as indicated in Fig. 3, may be supported on an insulated frame 43 which extends down between the convolutions of the spiral in proximity to the sides of the magnetostrictive element 42. The conductive elements 43 and 4 5 may be mounted upon this insulating element in any usual manner.

The insulating element may also be supported by the casing through the upper supporting plate 49. The conducting element 43 may itself have a coat of insulation on the outside, as, for instance, varnish or enamel or any other suitable material, but this is not needed where the conductive element does not come in contact with the magnetostriction spiral. The plate 40 upon which the magnetostrictive spiral is mounted may be supported in the manner described in the original application by means of the flange 50 extending over the flanged rim 5| of the casing 52 to which it is attached by means of the clamping ring 53 and the bolts 54, The same general principle as stated in the original application Serial No. 70,365 between cylindrical elements applies equally here with the distance between spiral convolutions and the principles also stated therein are equally well applied to the relations of the thickness of the plates. The plate or mass 453 in the present case is so proportioned that the system including the spiral convolutions 42 is established as a one-half wave length system wherein the nodes of the system occur in a plane normal to the convolution elements substantially near the plate d0. In accordance with this limitation the plate must have the proper thickness and mass and for the same material the thickness is preferably one-quarter wave length or less in the direction normal to the surface of the wave generated and propagated in the material.

In the operation of the system the coil as set up surrounding both the inside and the outside of the magnetostrictive member 42 tends to concentrate the flux in the magnetostrictive material. This concentration of flux is in the part of the spiral, as is pointed out just above, where a node of motion exists and where, therefore, the maximum variation of magnetostrictive fiux is obtained. Since the greatest variation of magnetic flux occurs around the node, it is only necessary for the conductive element 43 to extend upwards for a short distance along the magnetostrictive spiral, and the conductive element 43 is therefore shown as extending only a portion of the distance along the magnetostrictive element.

Having now described my invention, I claim:

1. A device for producing a beam of supersonic compressional wave energy comprising a plate having a large diameter compared with the wave length of the wave to be produced, a magnetostrictive sheet formed in a spiral with one edge of the sheet fixed to said plate, the spiral forming with the plate a vibrational system of onehalf wave length with the vibrational node in the spiral adjacent the plate, and a single copper turn following the spiral on one side from the outer end of the sheet to the center of the spiral, passing around the central end of the latter, and following the other side of the spiral to its outer end.

2. A device for producing mechanical vibrations of very high frequency comprising a plate member, a sheet element of magnetostrictive material formed as a spiral with one edge thereof fixed to said plate member, means positioned adjacent said spiral sheet for electrodynamically inducing high frequency alternating current flux in said spiral normal to said plate member a d means adapted to conduct current to said fi st named means.

3. A device for producing mechanical vibrations of very high frequency comprising a plate member, a' sheet of magnetostrictive material formed in a spiral and having one of its edges fixed to said plate, said plate and spiral forming together a vibrational system of one-half wave length with the vibrational node in the spiral adjacent the plate, means positioned adjacent said spiral member at the vibrational node thereof for electrodynamically inducing high frequency current flux in said spiral normal to said plate and means for conducting current to said means.

4. A device for producing mechanical vibrations of very high frequency comprising a plate member having a recessed portion at the back thereof extending substantially over its entire surface, a sheet of magnetostrictive material formed as a spiral and having its edges positioned in the recessed portion of said plate member, a metal of comparatively low melting point filling the spaces between the convolutions of the spiral and filling the recessed portion of said plate, conductive means enveloping the surface of said magnetostrictive sheet but positioned free from said plate for inducing alternating high frequency current flux in said spiral normal to said plate and means for conducting current to said conductive means.

5. A device for producing mechanical vibrations of very high frequency comprising a plate member, a sheet of magnetostrictive material formed in a spiral having equally spaced convolutions, means securing one of the edges of said spiral in said plate, the space between successive convolutions being less than the thickness of said plate, conductive means enveloping and adjacent the surface of said magnetostrictive sheet for inducing alternating high frequency current flux in said spiral normal to said plate and means for conducting current to said conductive means.

6. An acoustical apparatus comprising in combination a plate member, electromechanical energy interchanging means fixedly mounted on said plate, said means includin a spirally mounted magnetostrictive element in which each spiral is spaced from its adjacent spiral, the convolutions covering substantially the plate which has linear dimensions large as compared with the wave length of the wave in the propagating medium within which the apparatus is to operate.

7. An acoustical apparatus comprising in combination a plate member, electromechanical energy interchanging means fixedly mounted on said plate, said means including a spirally mounted element in which each spiral is spaced from its adjacent spiral, the convolutions covering substantially the plate which has linear dimensions large as compared with the wave length of the wave in the propagating medium within which the apparatus is to operate and a coil surrounding the spiral for energizing the same.

EDWIN E. TURNER, JR. 

